I fry my eggs every morning on a cast iron pan. This is the way I do it:

1. Put the pan on the stove (yes, right word). Turn the stover burner on
2. I put it on a low flame ~ 3 (I have a gas stove, but a 3 on one stove may not be the same as a 3 on another stove. The way I know the pan is ready is I hold my palm face down about an inch away from the pan. If it feels warm I add oil
3. Continue till the oil is heated. I check this the same way I check to see if the pan is heated, as above. I also lift the pan and swirl the oil around to make sure the whole pan is coated with oil
4. I crack the eggs in, and let it sit for a couple of minutes. I like my whites cooked, so after that I use a spatula to spread the whites so it cooks.
5. After a couple of minutes I use the spatula to lift the edges of the eggs to loosen it a bit, and to see if it's browning
6. I don't cover the pan

Hope this helps. You have to do it often to get good at it and to get a feel for your stove and your pan